It's not really a bug and I've had it myself in the past (that's why I know how to 'solve' it now).
It has something to do with your disks needed being checked but the info it BEING checked not been removed from registry
you can have a look at http://support.microsoft.com/kb/831426
HKLM/system/controlset001/control/session manager doe have (or need) an entry (REG_MULTI_SZ) 'BootExecute' with value 'autocheck autochk'
If you used a tool like O&O Defrag it might have added an entry into the register (sometimes a * is being added in the bootexcetute line) see http://www.wilderssecurity.com/archi...p/t-76703.html
I hope by now you will have enough info to understand the problem and solve it yourself